as name says ... two opposite corners of coil pack spark perfect,other 2 are on and off when they feel like it... changed all sensors, leads, plugs, coil pack, still the same.. any idea?

car - 1998 wrx uk spec classic.

 

Might be a wiring fault or injectors or crankshaft or camshaft sensor have u done a fault code test yet

 

have you just changed the cambelt?